Pen



FIG. 1 is a side, top, perspective view of the pen;

FIG. 2 is a left side view, the right side view being a mirror image thereof;

FIG. 3 is a top view;

FIG. 4 is a bottom view;

FIG. 5 is a front view; and,

FIG. 6 is a rear view. 

The ornamental design for a pen, as shown and described. 